If it were done when 'tis done, then 'twere well
It were done quickly…
--- W. Shakespeare, Macbeth 1-7
When you try something difficult, you would remember the first two lines of the Scottish assassin’s soliloquy told at Act 1 Scene 7 of Macbeth. Whether your action is fair or foul, you need your motivation & resolution to do it. If it were done when 'tis done, then 'twere well it were done quickly --- I render it simply: “if I can do it well, I have to do it quickly.” But Macbeth hesitates his action worrying about karma, because he can recognize that his ambition is foul that he will murder the king, who believes him:
MACBETH
If it were done when 'tis done, then 'twere well
It were done quickly: if the assassination
Could trammel up the consequence, and catch
With his surcease success; that but this blow
Might be the be-all and the end-all here,
But here, upon this bank and shoal of time,
We'ld jump the life to come. But in these cases
We still have judgment here; that we but teach
Bloody instructions, which, being taught, return
To plague the inventor: this even-handed justice
Commends the ingredients of our poison'd chalice
To our own lips.